Many medical conditions impact on the human spine anatomy. With the growing elderly population there are an increasing number of patients who are sustaining osteopenic or osteoporotic vertebral body compression fractures that creates significant morbidity and/or mortality for them. Traditional methods for dealing with these compression fractures are not always very effective. As a result, methods to strengthen the vertebral body have evolved with significant clinical improvement for affected patients. A common procedure for this is vertebroplasty in which a bone substitute, such as polymethylmethacrylate, hydroxylapatite compound or other material is injected into the vertebral body usually through a transpedicular approach, through the vertebral body pedicle, and sometimes through an extrapedicular approach. An improvement upon the vertebroplasty is the kyphoplasty procedure in which a balloon catheter is introduced usually through a transpedicular approach into the vertebral body and the catheter is then inflated to nearly restore the original vertebral body anatomy. When the catheter is deflated it leaves behind a cavitary void which is then filled with materials similar to the vertebroplasty. Both of these procedures have significant benefit for the patient in that they are usually performed through a percutaneous method which allows for outpatient management. Occasionally, treated patients may need to have an overnight hospital admission.
The use of vertebroplasty and kyphoplasty has extended to include management of vertebral body tumors, traumatic burst fractures and sometimes prophylactic management of impending fractures. A key element of eligible criteria for either procedure has traditionally been that the vertebral body must have an intact posterior vertebral body wall to avoid iatrogenic injury to the spinal cord secondary to leakage of injected material.
To reduce iatrogenic injury a number of safeguards have been instituted. Some of these safeguards include use of a radioopaque contrast material mixed with the injected material to visualize under radiographic imaging (fluoroscopy); performing the procedure in a controlled environment with biplanar fluoroscopic imaging (anterior-posterior and lateral imaging); miniaturization of equipment to prevent pedicle cortical wall breach, bilateral transpedicular approaches to vertebral bodies to maximize volume of injected material; limiting number of vertebral bodies injected at one setting to three or less vertebral bodies; limiting kyphoplasty to vertebral bodies below thoracic level 4 T4; and other strategies.
Inherent to successful outcome of procedures such as vertebroplasty, kyphoplasty, vertebral body biopsy, pedicle screw placement or others is a consistently same and reproducible access to the vertebral body. This access is usually a transpedicular approach, but can also be performed through an extrapedicular approach.
This invention provides a safe and reproducible method to transpedicular and extrapedicular approaches to any vertebral body. Furthermore, it includes specific embodiments to improve current methods of vertebroplasty, kyphoplasty, vertebral body biopsy and pedicle screw placement. This invention reduces radiographic imaging for these procedures to primarily anterior-posterior fluoroscopic visualization and can be utilized in either a percutaneous or open surgical environment with pedicle screw instrumentation present or absent.
The critical parameters for performing any of these procedures are through knowledge of the pedicle diameter, length and trajectory and then actual placement of instruments and/or screws. To date many of the image guided systems allow for manual determination of these parameters and to improve a surgeon's manual performance in these procedures. As of yet, no invention or system is available which will automatically determine ideal pedicle diameter, length, trajectory and actual placement of instruments or screws.